The present invention relates to a portable terminal device having display means such as a liquid crystal display (LCD), and more particularly, to transmission of various types of information items to a user by utilization of backlight colors of display means.
As represented by a portable telephone, recent portable terminal devices have been designed in pursuit of a compact, lightweight, and high-performance portable device. The majority of recent portable telephones employ an LCD module. Further, many of the LCD modules are provided with backlight so that characters or figures indicated on display means can be viewed in darkness, and an LED or EL (electroluminescence) is used as the light source for backlight.
As shown in FIG. 7, a conventional portable terminal having a backlight function comprises display means 40 for indicating characters or figures, light-emitting means 30 which serves as the light source for backlight, drive means 20 for actuating the light-emitting means 30, and control means 10 for controlling the drive means 20. The light-emitting means 30 comprises a first light-emitting diode 301 and a second light-emitting diode 302, which emits light of identical wavelength. The drive means 20 comprises a first resistor 201 for limiting an electric current flowing to the first light-emitting diode 301, a second resistor 202 for limiting the electric current flowing to the second light-emitting diode 302, and a transistor 300 which applies a drive voltage and shuts off the supply of drive voltage.
When the user presses any key of the portable terminal device, the control means 10 is activated, and an electric current is supplied to the first light-emitting diode 301 and the second light-emitting diode 302 of the light-emitting means 30. The first light-emitting diode 301 and the second light-emitting diode 302 emit light rays 501 and 502 of the same wavelength. As a result, characters or figures indicated on the display means 40 become sharply visible.
Some portable devices are configured in such a way that the light-emitting means is activated when the control means 10 detects darkness.
However, as the conventional portable terminal device becomes compact and lightweight, the effective area of a display screen of the display means 40 is also reduced, thus limiting the number of characters or the size of figure which can be displayed. As a result, it becomes necessary for the user to perform operations according to complicated procedures in order to obtain required information, or it becomes difficult for the user to see display characters or figures which are reduced in size. These problems make it difficult for children or the aged to use a portable terminal device.
The present invention has been conceived to solve the problems in the conventional portable terminal device, and the object of the present invention is to provide a portable terminal device capable of instantaneously transmitting various information items to the user by utilization of backlight of the display means.
A portable terminal device according to the present invention is capable of changing the color of backlight of the display means according to the contents of information to be transmitted.
To this end, the user can instantaneously ascertain information by means of the color of backlight of the display means without reading characters or figures indicated on the display means. Accordingly, information becomes easily understandable even for children and the aged, thereby enabling correct understanding of information even in darkness.
According to a first aspect of the present invention, there is provided a portable terminal device having backlight display means, wherein the color of backlight of the display means can be changed according to the content of information to be transmitted, thereby enabling a user to instantaneously understand the information from the backlight color.
According to a second aspect of the present invention, there is provided a portable terminal device including display means for indicating characters and figures, light-emitting means for emitting exposing light to be used as backlight of the display means, drive means for activating the light-emitting means, and control means for controlling the drive means, wherein
the light-emitting means emits exposed light rays having at least two wavelengths;
the control means controls the drive means according to the content of the information to be transmitted to the user in such a way that the wavelength of the exposing light originating from the light-emitting means is changed, thereby enabling the color of backlight of the display means to be changed according to the content of the information to be transmitted.
According to a third aspect of the present invention, the light-emitting means has at least two light-emitting elements which emit light rays of different wavelengths, and the control means controls the drive means to thereby switch on or off a single light-emitting element which emits light of a single wavelength or to thereby cause a plurality of light-emitting elements to simultaneously emit a plurality of light rays of different wavelengths. More specifically, the control means switches on or off a light-emitting element which emits light having a single color or causes a plurality of light-emitting elements to simultaneously emit light, thereby giving out a mixed light ray. As a result, the color of backlight is changed.
According to a fourth aspect of the present invention, the portable terminal device further comprises detection means for detecting the voltage level of a drive battery of the portable terminal device and setting means for setting a threshold value for the voltage level of the battery. When the voltage level detected by the detection means reaches the threshold value, the control means controls the drive means, thereby switching the wavelength of the light originating from the light-emitting means. The user can instantaneously ascertain a drop in the voltage level of the drive battery from the change of backlight color of the display means from ordinary color.
According to a fifth aspect of the present invention, the portable terminal device further comprises reading means for reading from a received signal a signal for specifying the color of backlight of the display means. On the basis of the signal which is read by the reading means and specifies backlight color, the control means controls the drive means, thereby changing the wavelength of the light originating from the light-emitting means. If a calling party using another portable terminal device originates a call while specifying backlight color, the backlight of the display means of the portable terminal device of the called party assumes the specified color. Therefore, if the user makes a prior arrangement with supposed calling parties regarding designation of backlight color, from the backlight color the called party can realize an incoming call is from a specific calling party.
According to a sixth aspect of the present invention, the portable terminal device further comprises
reading means for reading from a received signal the phone number of the calling party;
storage means for storing at least one phone number; and
comparison means for comparing the phone number of the calling party read by the reading means with the phone numbers stored in the storage means. On the basis of the result of the comparison performed by the comparison means, the control means controls the drive means, thereby switching the wavelength of the light originating from the light-emitting means. Upon receipt of an incoming call from the calling party registered in the storage means, the called party can identify the calling party from the color of backlight of the display means.
According to a seventh aspect of the present invention, the portable terminal device further comprises
measurement means for measuring the electric field level of a received signal; and
setting means for setting a threshold value for the electric field.
When the electric field level measured by the measurement means reaches the threshold value, the control means controls the drive means, thereby switching the wavelength of the light originating from the light-emitting means. From the color of the backlight of the display means, the user of the portable terminal device becomes aware that he is outside of a normally-receivable range.